1. Field of the Invention
The present invention relates to a method of and to a system for controlling the supply of electrical power to an electrically propelled vehicle designed to operate in an external power supply mode or in an autonomous power supply mode as a function of the presence or the absence of an external power supply infrastructure along the route of the vehicle. The invention relates in particular to supplying electrical power to trams.
2. Description of the Prior Art
Patent application FR-A1-2 782 680 discloses a system of supplying power to electrically propelled vehicles enabling operation of public transport vehicles, such as high-capacity trams, without using an uninterrupted power supply via overhead contact lines. The system includes an autonomous power supply system on board the vehicle, consisting of an electric motor with a heavy flywheel, and stops provided with an overhead contact line for recharging the autonomous power supply system via a pantograph carried by the vehicle.
The above power supply system has the drawback of necessitating detection of the connection of the pantograph to the overhead contact line to optimize management of the changeover from one power supply mode to the other and the performance of the power supply system. To optimize the performance of the vehicle, it is further necessary for the vehicle to be always supplied with electrical power by the autonomous power supply system or by the overhead contact line, which leads to transition phases during which the vehicle is connected both to the autonomous power supply system and to the overhead contact line. During these transition phases the autonomous power supply system is active, i.e. used as a power generator, with an output voltage greater than the overhead contact line voltage, which causes a loss of power from the autonomous power supply system to the overhead contact line, accompanied by fast and costly discharging of the autonomous power supply system. Another drawback of the above power supply system is the possibility of electrical arcing when the pantograph separates from the overhead contact line, causing rapid wear of these components.
The invention therefore aims to remedy the above drawbacks by proposing a method of and a system for controlling the supply of electrical power to an electrically propelled vehicle operating in an autonomous power supply mode or in an external power supply mode, which method and system are adapted to detect connection of the vehicle to an external power supply infrastructure and to optimize management of transition phases between the two power supply modes and are simple and economic to put into practice.